Half our fish are now farmed

September 6, 2006By Emma MarrisThis article courtesy of Nature News.

Aquaculture boom spells good and bad news.

There's a 43% chance that your fish dinner spent its life on a farm, rather than roaming wild. That's up from just 9% in 1980, according to this year's UN Food and Agriculture Organization (FAO) report, released 4 September at an aquaculture meeting in New Delhi, India.

The report outlines the immense boom in aquaculture. By 2004, 45.5 million tonnes of fish were being farmed, compared to 60 million tonnes of fish caught for human consumption.

The annual global wild fish catch has now stayed steady for decades, the authors note, and has probably maxed out. So the increasing demand from the world's swelling population must be met with farmed fish, they say.

It is unclear whether this rise is a good or bad thing for the planet. Whereas farming fish takes some pressure off over-fished wild populations, it also raises its own environmental concerns.

Fishy food

Disease and parasites can spread from the densely kept farmed fish to their wild cousins. Escapees from pens can disrupt the local gene pool. Farms can release large amounts of excrement and leftover feed into the water, which can spur algae blooms and kill off local wildlife. And farming doesn't always spare wild catch: some carnivorous farmed fish are fed with wild catches of smaller fish, such as sardines or herring.

To top everything off, there has also been uproar in Mexico and California over the alleged practice of shooting sea lions looking for a captive lunch in farmer's nets (see ' Aquaculture: Fishing for trouble' ).

Nevertheless, the industry helps to feed the developing world. Aquaculture makes food supplies more secure and brings money to communities. One area that hasn't seen a big boom in fish farming sub-Saharan Africa is being encouraged by non-governmental organizations to take it up.

The FAO estimates that the world will need an additional 40 million tonnes of aquatic food per year to sustain the growing population by 2030.

Rohana Subasinghe, secretary of the FAO's subcommittee on aquaculture, says the industry is getting greener all the time. "We went through a learning phase; we made mistakes and we corrected them. There was some uncontrolled development but over the past decade and a half we have made quantum leaps in improving environmental impacts of the sector," he says.

He adds that he finds it imperative to bring aquaculture to Africa in order to ease starvation. "It has a tremendous opportunity to provide food for people who can't afford high-value food," he says. "It is our duty to focus on Africa."